Electrochemical properties of Al and Al alloys relevant to corrosion protection in seawater environments

Electrochemical characteristics of Al-Mg alloy in seawater for leisure ship: Stress corrosion cracking and hydrogen embrittlement

“…The current density increased as the potential shifted to a more negative value. This potential range corresponded to the generation of atomic hydrogen (H + +e→H) or the production of molecular hydrogen from atomic hydrogen (H + +e+H→H 2 , H+H→H 2 ), resulting in the acceleration of activation polarization and an increase in the current density [6,11]. We concluded that atomic hydrogen affected the potential at which the crossover occurred.…”

“…However, the high current densities remained relatively constant. In a previous investigation [6], the current density increased suddenly when the applied potential shifted beyond the protection potential range in either the anodic or cathodic directions. The highstrength 7075 alloy had the highest current densities.…”

“…The 5456 alloy has the lowest potential, while the 7075 alloy has the highest, which indicates that the 7075 alloy is most affected by hydrogen embrittlement. During the polarization tests for the 5456-H116 Al alloy, the destruction and formation of the passivity film in the anodic polarization curve were repeated [6,11]. The current density at the potential that generated hydrogen gas increased abruptly in the cathodic polarization curve.…”

“…However, in seawater, the passive films formed during anodic polarization are subsequently destroyed by the Cl − in the solution; the passivity continues to develop due to the self-healing capacity of Al. In previous investigations [6,11], the current density of the 5456 alloy decreased abruptly at a potential of −0.3 to 0.4 V, while the current density of the 7075 alloy increased with the potential during anodic polarization without passivity developing. The current density of the 5456 alloy remained less than that of the 1050 alloy.…”

“…In addition, FRP ships are small. As with wooden vessels, larger craft cannot detect FRP ships by radar since their composite materials reflect radar waves poorly [4][5][6]. According to data collected by the Ministry of Maritime Affairs and Fisheries, a large proportion of ship accidents involve these vessels, comprising 72.4% of all marine accidents between 1998 and 2002 and approximately 58% of all collisions involving fishing boats [7].…”